<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style>
        li+li {
            color: tomato;
        }
    </style>
</head>

<body>
    <ul>
        <li>前端</li>
        <li>后端</li>
        <li>测试</li>
    </ul>
    <ol>
        <li>电脑</li>
        <li>鼠标</li>
        <li>键盘</li>
    </ol>
</body>

</html>